Rewinders convert large industrial parent rolls into retail-sized rolls of bathroom tissue, paper towels and the like. Center rewinders are described in U.S. Reissue Pat. No. 28,353 (hereafter xe2x80x9cthe ""353 patentxe2x80x9d). Center rewinders are adapted to wind a web on a core that is rotated by a turret.
Cut-off and transfer is a critical operation in rewinding rolls. The web must be severed to cease the winding of a roll. Then, the leading edge of the severed web must be transferred to a new core. Then, the new core must be rotated to begin winding of a new roll. These steps must be accomplished repeatedly and reliably while the web is moving at high speed. It is desirable that each roll reveals an exact sheet count so the web is wound uniformly.
In the industry, the term xe2x80x9cbedrollxe2x80x9d usually refers to the main winding roll of a rewinder. For example, in the ""353 patent a bedroll is used with a chopper roll to sever the web after a predetermined length of web has been wound onto a log. The bedroll transfers the leading edge of the severed web to a new core in a continuous winding process. In the apparatus disclosed in the ""353 patent, the severing and transfer mechanism includes a series of pins, cut-off blades, and transfer pads, all of which are mounted within the bedroll. When the severing and transfer mechanism is unlatched, the pins hold the web against the rotating bedroll while the web is severed by interaction of the chopper roll with blades that emerge from the bedroll.
Center winders commercially available in the industry and sold by Paper Converting Machine Company of Green Bay, Wis. may include moveable pins in a bedroll for holding the leading edge of the severed web, and for carrying the leading edge into position. Further, a latch mechanism may be used for retaining the pins in an inoperative position until the web is to be severed. A cut-off knife may be fixed in a chopper roll and the cut-off blade in the bedroll may be movably mounted.
Bedroll blade and pin assemblies must be changed periodically for maintenance. In such operations, it is desirable to replace or adjust assemblies without adversely affecting critical setup dimensions and fine tolerances. In conventional designs, the blade assembly includes clamps that must be loosened on the cross-shaft to replace parts. The setup dimensions between bedroll pins, pads and the mandrel must be reestablished each time the parts are changed using conventional apparatus. The top bedroll cover usually must be removed to access such mechanical assemblies. It is common, therefore, for a large amount of machine xe2x80x9cdown timexe2x80x9d to be incurred in changing and re-setting such blades and pins. Furthermore, there exists a risk of error in setting the clearance between the pins and the mandrel, which can be a time consuming and difficult problem.
U.S. Pat. No. 4,280,669 (the xe2x80x9c""669 patentxe2x80x9d) discloses an automatic web rewinder for a tensioned web. In FIG. 10 of the ""669 patent, a configuration that employs individual pins is shown. Such pins must each be replaced separately, resulting in a relatively long and difficult maintenance procedure that must be periodically performed on such apparatus.
What is needed in the industry is an improved design for a blade and pin assembly that facilitates a change of pins and blades without undesirably affecting critical setup tolerances. Furthermore, an apparatus and method that minimizes the amount of labor involved in changing pins and/or blades would be desirable. An assembly that can reduce the amount of down time incurred in repair operations would be useful.
The invention comprises an apparatus or device and method for severing and carrying a sheet or web in a winding operation. In one embodiment of the invention, a first blade and a second blade are provided, in which the first blade and second blade are connected and spaced apart a predetermined distance to form a gap. The first and second blades are adapted to bear against the surface of a web, further wherein the gap is sized so as to receive another blade or tearing member between the first blade and second blade in severing a web or sheet.
Furthermore, in one application of the invention, a unitary elongated mandrel is connected to at least the first blade, the mandrel comprising a plurality of spaced pins projecting from the mandrel and spaced along its length, the pins being configured for piercing and carrying a severed web.
The device of the invention typically is mounted within a bedroll which rotates to feed a sheet or web. The sheet may include paper, textiles, synthetics, or other fabrics or webbing. In many instances, the sheet or web fed by the bedroll previously has been perforated, so that tearing or severing requires relatively little force. The device also may include a spacer between the first blade and second blade to set the space of the gap at a predetermined distance that is most effective for severing or tearing the sheet.
In many applications of the invention, a unitary elongated mandrel having a series of pins along its length is configured to project from the exterior surface of the bedroll at a point in time just prior to the web being severed, to hold the web in place against the bedroll once the web has been separated. A pin assembly may be movable from a first position in which pins are held beneath the outer circumference of the bedroll, to a second position in which all or some of the pins project from the outer surface of the bedroll.
The device of the invention also may include pins that are oriented in substantially the same direction. Replacement of the unitary elongated mandrel with its associated pins usually may be accomplished by mounting the unitary elongated mandrel upon the front side of the clamp.